Area Forecast Discussion
Issued by NWS Honolulu, HI

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000
FXHW60 PHFO 131333
AFDHFO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
333 AM HST SAT FEB 13 2016

.SYNOPSIS...
LOCALLY BREEZY EASTERLY TRADE WINDS WILL PERSIST THROUGH SUNDAY
ACROSS MAUI COUNTY AND THE BIG ISLAND...WHILE GENTLE EAST TO
SOUTHEAST WINDS ALLOW FOR LEEWARD LAND AND SEA BREEZES ON OAHU
AND KAUAI. STABLE CONDITIONS WILL FOCUS PASSING SHOWERS OVER
WINDWARD SLOPES...MAINLY ON MAUI AND THE BIG ISLAND. NORTHEASTERLY
TRADE WINDS WILL INCREASE EARLY NEXT WEEK AS STRONG HIGH PRESSURE
BUILDS NORTHWEST OF THE STATE. SHOWERS ARE EXPECTED TO INCREASE
OVER THE AREA AS FRONTAL REMNANTS ARE CARRIED ACROSS THE STATE
FROM MONDAY NIGHT THROUGH WEDNESDAY.

&&

.DISCUSSION...
SCATTERED SHOWERS EMBEDDED IN THE TRADE WIND FLOW HAVE CONTINUED
TO MOVE INTO SOME WINDWARD AREAS OF THE BIG ISLAND...MAUI AND
MOLOKAI OVERNIGHT...AND SHOWERS HAVE PERSISTED ALONG THE WINDWARD
OAHU COAST AND OVER THE KOOLAU RANGE AS WELL. DRY WEATHER
PREVAILS OVER THE REMAINDER OF THE STATE. SURFACE ANALYSIS DEPICTS
HIGH PRESSURE CENTERED FAR TO THE NORTHEAST...WITH A RIDGE
EXTENDING WESTWARD TO THE NORTH OF THE ISLANDS...AND A COLD FRONT
OVER THE NORTHWESTERN HAWAIIAN ISLANDS ABOUT 700 MILES WEST-
NORTHWEST OF KAUAI. THE TRADE WINDS ARE STRONGEST OVER THE EASTERN
HALF OF THE STATE...WHILE WEAKER EAST-SOUTHEAST FLOW PREVAILS
OVER THE WESTERN HALF. MIMIC-TPW SATELLITE IMAGERY SHOWS A
GENERALLY DRY AND STABLE AIRMASS SURROUNDING THE STATE...ALTHOUGH
THE 12Z HILO SOUNDING SHOWS A BIT MORE MOISTURE THERE WITH THE
INVERSION UP TO 10K FEET AND PWAT OF 1.14 INCHES. THE 12Z LIHUE
SOUNDING REMAINED QUITE DRY WITH THE INVERSION BASE NEAR 7000
FEET AND PWAT JUST BELOW 0.9 INCHES. WATER VAPOR IMAGERY SHOWS A
STRONG MID LEVEL RIDGE CENTERED ALMOST DIRECTLY OVER THE STATE.

LITTLE CHANGE IS EXPECTED THROUGH THE WEEKEND. HIGH PRESSURE WILL
REMAIN FAR NORTHEAST OF THE STATE...DRIVING MODERATE EASTERLY FLOW
ACROSS THE BIG ISLAND AND MAUI COUNTY...VEERING TO GENTLE
EAST/SOUTHEAST FLOW OVER OAHU AND KAUAI. SHOWERS WILL BE MOST
PREVALENT OVER WINDWARD SECTIONS OF THE BIG ISLAND AND MAUI...BUT
EVEN THERE RAINFALL AMOUNTS WILL BE RELATIVELY LIGHT DUE TO
LIMITED MOISTURE. MAINLY DRY CONDITIONS WILL PREVAIL OVER OAHU AND
KAUAI...AS THIS FLOW REGIME WILL KEEP THOSE ISLANDS IN THE RAIN
SHADOW OF THE BIG ISLAND. SCATTERED SHOWERS WILL BE POSSIBLE OVER
WINDWARD OAHU AT TIMES...AS THAT AREA CAN BE FAVORED FOR RAINFALL
IN EAST-SOUTHEAST FLOW. AFTERNOON SEA BREEZES ACROSS LEEWARD
SECTIONS SHOULD PRODUCE SOME CLOUDS BUT LITTLE RAINFALL IS
EXPECTED. WINDS ARE EXPECTED TO SHIFT BACK TO A MORE TYPICAL TRADE
WIND DIRECTION BY LATE SUNDAY AS A COLD FRONT APPROACHES KAUAI.

A TRANSITION TO A BREEZY AND RATHER WET TRADE WIND PATTERN IS
FORECAST DURING THE FIRST HALF OF NEXT WEEK. STRONG HIGH PRESSURE
BUILDING FAR NORTHWEST OF THE STATE WILL PUSH A DISSIPATING
FRONTAL BOUNDARY CLOSE TO KAUAI ON MONDAY. AN INCREASE IN
RAINFALL IS LIKELY ON KAUAI BY MONDAY NIGHT AS THE FRONT DRIFTS
OVER THAT ISLAND...WITH THE BAND OF MOISTURE SPREADING OVER OAHU
AND MAUI COUNTY ON TUESDAY AND TUESDAY NIGHT AS THE DISSIPATING
FRONT CONTINUES DRIFTING TO THE SOUTHEAST. THE GFS AND ECMWF
CONTINUE TO DEPICT BREEZY/GUSTY TRADE WINDS SPREADING ACROSS THE
STATE MONDAY NIGHT AND TUESDAY...AND CONTINUING ON WEDNESDAY.

LONGER RANGE MODELS DEPICT THE STRONG HIGH TO OUR NORTHWEST
SINKING GRADUALLY SOUTHWARD WEDNESDAY NIGHT AND THURSDAY. THIS
PUSHES THE LINGERING MOISTURE SOUTH OF THE BIG ISLAND AND BRINGS A
MUCH DRIER AIRMASS OVER THE STATE FOR THE LATER PART OF NEXT WEEK.
BREEZY TRADES WILL CONTINUE...ALTHOUGH WINDS MAY NOT BE QUITE AS
STRONG AS THOSE OBSERVED EARLIER IN THE WEEK.

&&

.AVIATION...
VFR WILL PREVAIL OVER THE ISLANDS THROUGH SATURDAY. HOWEVER...BRIEF
MVFR CONDITIONS WITH LOWER CEILINGS AND SHOWERS ARE POSSIBLE ACROSS
E AND SE SECTIONS OF THE BIG ISLAND AND EAST MAUI...AND MAUKA AND
WINDWARD SECTIONS OF WEST MAUI AND THE SMALLER ISLES.

NO AIRMETS ARE CURRENTLY IN EFFECT.

&&

.MARINE...
NORTHWEST SWELL HAS CONTINUED TO DECLINE BOTH AT THE NEARSHORE
BUOYS AND AT BUOY 51001 DURING THE NIGHT...AND THE EARLIER HIGH
SURF ADVISORY FOR NORTH FACING SHORES WAS DROPPED SHORTLY BEFORE
MIDNIGHT. SURF WILL REMAIN BELOW ADVISORY LEVELS ON ALL SHORES
TODAY AND TONIGHT...THEN A MODERATE NORTHWEST SWELL APPEARS SET
TO PRODUCE THE NEXT ROUND OF LOW-END ADVISORY LEVEL SURF ON NORTH
AND WEST FACING SHORES SUNDAY INTO MONDAY. INCREASING NORTHEASTERLY
TRADES MAY ALSO PRODUCE HIGH SURF ALONG EAST FACING SHORES OF SOME
ISLANDS ON TUESDAY AND WEDNESDAY.

THE FRIDAY EVENING ASCAT PASS REVEALED WINDS SPEEDS RUNNING LOWER
THAN EXPECTED ACROSS THE WATERS FROM MAUI THROUGH KAUAI...BUT HIGH
RESOLUTION MODEL GUIDANCE INSISTS THAT THE WINDS SHOULD INCREASE
CONSIDERABLY BY MORNING...AND WILL KEEP THE EXISTING SMALL CRAFT
ADVISORY /SCA/ IN PLACE TODAY FOR ALL OF THE SAME ZONES EXCEPT
FOR MAALAEA BAY. THE SCA MAY NEED TO BE EXTENDED INTO TONIGHT FOR
SOME ZONES AROUND THE BIG ISLAND...BUT WILL LET THE DAY SHIFT MAKE
THAT DECISION. THE SCA COULD BE EXPANDED FOR SEAS ON SUNDAY
DUE TO ANOTHER NORTHWEST SWELL...AND WILL LIKELY BE NEEDED ACROSS
THE ENTIRE AREA ONCE AGAIN EARLY NEXT WEEK FOR AREAS OF STRONG
NORTHEAST TRADES AND HAZARDOUS SEAS.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
SMALL CRAFT ADVISORY UNTIL 6 PM HST THIS EVENING FOR MAUI COUNTY
WINDWARD WATERS-MAALAEA BAY-PAILOLO CHANNEL-ALENUIHAHA CHANNEL-
BIG ISLAND WINDWARD WATERS-BIG ISLAND LEEWARD WATERS-BIG ISLAND
SOUTHEAST WATERS.

&&

$$

DISCUSSION/MARINE...JACOBSON
AVIATION...KINEL


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